Contention resolution covering all ports of a data switch

ABSTRACT

A communication network has one or more interconnected data switches having I/O ports and at least one virtual port. The communication network further has means for subjecting the ports to one and the same contention resolution process.

The present invention relates to a communication network comprising oneor more interconnected data switches having I/O ports and at least onevirtual port.

The present invention also relates to a data switch for application inthe communication network, and to a contention resolution method.

Such a communication network and contention control method are knownfrom U.S. Pat. No. 6,411,617 B1. The known communication network systemcomprises a plurality of network nodes, each including a network datapacket switch. The data switch has input/output (I/O) ports and virtualports formed by dedicated input ports and dedicated output ports.Network node congestion control is selectively applied at the dedicatedoutput port of the network switch. The dedicated output ports, whichgenerally show a broader bandwidth than the bandwidth of regular inputand output ports, are coupled through virtual paths to external orintegrated extender devices for implementing a functionality thataccompanies the data switch.

It is an object of the present invention to provide a simplifiedcommunication network and contention control method, which alleviatesthe burden on required associated soft- and hardware.

Thereto the communication network according to the invention ischaracterized in that the communication network further comprises meansfor subjecting said ports to one contention resolution process.

It is an advantage of the communication network and method according tothe present invention that it is found, despite the fact that virtualports take a special position relative to input and output (I/O) portsof the data switch, that the problem of contention and in particularcontention resolution may be seen as a problem that may includecontention resolution on one or more input and/or output ports, and oneor more dedicated or virtual ports. With this notion contention at bothone or more I/O ports and one or more virtual ports can be resolvedcombined, as contention at a virtual port of the data switch simply maybe treated as contention on some I/O port of the switch. This saves bothassociated software and hardware, control, as well as preciousprocessing time.

In an embodiment of the communication network according to theinvention, the at least one virtual port is a virtual input port or avirtual output port.

This way contention on either the virtual input port or the virtualoutput port may be treated as contention on some input port or on someoutput port of the data switch.

In a further embodiment of the communication network according to theinvention, the at least one virtual port is an internal virtual port oran external virtual port.

Advantageously no distinction has to made when it comes to the treatmentof contention with regard to internal or external virtual ports of thedata switch.

In a still further embodiment of the communication network according tothe invention, the at least one virtual port is an addressable virtualport.

Advantageously various ways of addressing the virtual port are possible.

In still another embodiment of the communication network according tothe invention, the at least one virtual port is coupled to at least oneresource. Such a resource may either be an internal or an externalresource, whereas such a resource may comprise one or more of thefollowing means: means for testing, means for debugging, means forprogramming, means for configuring. Such means may be associated witheach data switch, and will generally be controlled by a system ornetwork manager.

Further dependent claims outline other merits and advantageous featuresof preferred embodiments of the invention.

At present the communication network and contention resolution methodaccording to the invention will be elucidated further together withtheir additional advantages, while reference is being made to theappended drawing, wherein similar components are being referred to bymeans of the same reference numerals. In the drawing:

FIG. 1 shows a schematic view of a communication network comprisingseveral data switches;

FIGS. 2(a), 2(b) show schematic views of data switches provided withinternal and external resources respectively;

FIGS. 3(a), 3(b), and 3(c) show possible ways of implementing virtualinput ports and virtual output ports on the data switches of FIGS. 2(a),and 2(b); and

FIG. 4(a), 4(b) and 4(c) show possible ways of addressing virtual portson the data switches for application in the communication network ofFIG. 1.

In present day systems-on-chip and network-on-chip architectures thereis the challenge of managing the complexity of designing chipscontaining billions of semiconductor components. Wires and busses are nolonger suitable for dealing with the dynamic communication required inthose architectures. Communication services of various types providedata communication in a communication network 1 as shown in FIG. 1. Thecommunication network 1 comprises interconnected data switches 2, alsoknown as notes, routers, matrix switches or the like. The data switchescomprise input ports 3, and output ports 4. Control means CR are coupledto each of the switches 2 for connecting selected inputs 3 to selectedoutputs 4 in order to secure reliable data communication throughout thenetwork 1 and to other networks (not shown), such as for example theInternet.

In practice such a data switch 2 is also capable of performingfunctions, like for example testing, debugging, programming orconfiguring, in order to function as required in the network. Functionaldata necessary for implementing these functions in one or more of thedata switches 2 is associated with routing information that can eitherbe attached to the data to be communicated, like in a header such aswith packet switching, or may be sent to the switch 2, like in timedivision switched schemes. The functional data which is meant for aparticular switch 2 or for a group of switches 2 is routed to theparticular switch 2 and provided at one or more of the input ports 3 ofthe switch 2.

The switch 2, as shown in FIGS. 2(a) and 2(b) has internal and/orexternal virtual ports 5, which are coupled to either internal orexternal resources 6 in the data switch 2, which resources 6 form thevarious means that are capable of performing the associated abovementioned data switch functions, based on the functional data.

The input ports 3 if properly controlled couple the functional data anthe input port 3 concerned to the relevant addressed virtual output portor virtual output ports 5 in order to provide data input to theresources 6. In fact one could say that a regular port of a data switchbecomes a virtual port if that port is coupled to a resource, whichresource performs functions that are associated to the data switch 2.However the fact that the virtual port is excluded from regular datatransfer through the switch 2 also excluded it from regular contentionresolution processes.

Various implementations of ports of the data switch 2 are shown in FIGS.3(a), 3(b) and 3(c). The various resources 6 perform the requiredfunctions. Conversely the resources 6 may want to send data to a virtualinput port 7, which data may be sent through appropriate output ports 4to one or more other data switches 2 in the network 1. For example FIG.3(a) shows a case where a monitor as resource 6 only provides data to avirtual input port 7 of the switch 2, and FIG. 3(b) shows a case wherethe monitor only receives data from virtual output port 5. The number ofinput ports 3, 7 does not have to be equal to the number of output ports4, 5.

Under normal circumstances a method is being applied for avoidingcontention, either on input ports 3 or on output ports 4 of the dataswitch 2. Such a method is implemented in contention resolution means CRschematically shown in FIGS. 2, 3, 4, (a), (b), (c), as the case may be.Input contention arises if an input port 3 wants to address more thantwo output ports 4, and output contention arises if an output port 4 isaddressed by two or more input ports 3. A proper scheduling ofconnections between input and output ports leads to a resolution of suchcontentions. If for example the well known matrix scheduling algorithmwith or without a slot table or any other suitable contention resolutionalgorithm is used by the contention resolution means CR for handlingcontention on input ports or output ports 3 or 4 that very samealgorithm can now be used to resolve contention on the virtual inputports 7 and/or virtual output ports 5. So now contention on a local,either internal or external resource 6 may be treated by the means CR ina similar way as contention on any other input 3 or output port 4 of thedata switch. No dedicated contention algorithm is required for solvingcontention problems on virtual ports 5, 7.

Normally any matrix data scheduling algorithm requires the addressing ofports. FIGS. 4(a), 4(b) and 4(c) show possible ways of also addressingthe virtual ports 5, 7 of the data switch 2 in order to easily apply thecontention resolution method. The usual way of addressing the I/O ports3, 4 is to number them. This numbering may now be extended to thevirtual ports so that all the ports 3, 4, 5, and 7 are subjected to onecontention resolution process. Several options are shown in the figures.FIG. 4(a) shows that the numbering of the ports 3, 4 is extended to thededicated or virtual ports 5, 7. Such a possible method is very simple.FIG. 4(b) shows that the numbering of the virtual ports 5, 7 starts allover again, which has the advantage that a special routing mode could beintroduced which exploits the fact that fewer amounts of bits arerequired for addressing the I/O ports 3, 4 and the virtual ports 5, 7respectively. The embodiment of FIG. 4(c) shows a combination of theaforementioned two methods, but at the expense of requiring more bitsfor addressing.

1. A communication network comprising one or more interconnected dataswitches having I/O ports and at least one virtual port, characterizedin that the communication network further comprises means for subjectingsaid ports to one contention resolution process.
 2. The communicationnetwork according to claim 1, wherein the at least one virtual port is avirtual input port or a virtual output port.
 3. The communicationnetwork according to claim 1, wherein the at least one virtual port isan internal virtual port or an external virtual port.
 4. Thecommunication network according to claim 1, wherein the at least onevirtual port is an addressable virtual port.
 5. The communicationnetwork according to claim 1, wherein the at least one virtual port iscoupled to at least one resource.
 6. The communication network accordingto claim 5, wherein the at least one resource is an internal or externalresource.
 7. The communication network according to claim 6, wherein theat least one resource comprises one or more of the following means:means for testing, means for debugging, means for programming, means forconfiguring.
 8. The communication network according to claim 7, whereinthe at least one resource are means for one of the associated dataswitches.
 9. A data switch for application in the communication networkaccording to claim 1, the communication network comprising one or moreinterconnected data switches having I/O ports and at least one virtualport, characterized in that the communication network further comprisesmeans for subjecting all said ports to one contention resolutionprocess.
 10. A contention resolution method, characterized in that themethod involves contention resolution covering ports of at least onedata switch having I/O ports and at least one virtual port.